Lubricant grease compostion containing surface esterified organic siliceous organophilic solid thickener



2,805,994 Patented Sept. 10, 1957 ice LUBRICANT GREASE COMPOSITION CG'NTAIN- ING SURFACE ESTERIFIED ORGANIC SILI- CEOUS ORGANOPHILIC SOLID 'l'lllCKEN'ER Hubert J. Liehe and Wilbur L. Hayne, Jr., Hammond, Ind., assignors to Standard Oil Company, Chicago, 1th., a corporation of Indiana No Drawing. Application December 27, lib-=4, Serial No. 477,946

6 Claims. (Cl. 252-48) This invention relates to novel lubricant grease compositions comprising an organic lubricant vehicle thickened with a silica product. More particularly, it relates to water resistant silica thickened greases containing certain alkyl or alkenyl derivatives of succinic acid or succinic anhydride to impart rust preventive properties to such greases.

For many years, the possibility of thickening lubricating oils with certain finely divided solids such as carbon black, asbestos, mica, silica gel, etc. has been well recognized, and for certain applications substantial quantities of grease embodying same have been employed. In general, however, greases embodying soap thickeners have enjoyed substantially greater acceptance because of their superior ability to lubricate highly machined surfaces. increasingly higher speed operation of modern equipment, however, has resulted in service temperatures beyond the melting points of soaps and has awakened real interest in silica thickened greases which have much better high temperature stability.

Silica thickened greases, in general, have suffered from a lack of resistance to disintegration by water and a very high instance of rust on surfaces lubricated therewith. Recently several improved water resistant silica thickened greases have been developed. One very substantial problem which still prevails, however, is rapid corrosion of surfaces lubricated by such greases.

It is an object of the present invention to provide hydrophobic silica thickened greases comprising organic lubricating vehicles which may be employed in high speed modern equipment under varying conditions of moisture and heat without allowing any substantial amount of corrosion of lubricated surfaces. A further object is to provide hydrophobic silica thickened lubricant greases which are particularly effective at temperatures above the melting points of most soaps heretofore employed in greases and which have excellent rust preventive properties. These and additional objects and advantages of the present invention will be apparent from the ensuing description.

In accordance with the present invention, hydrophobic silica greases embodying an organic lubricant vehicle, e. g. a petroleum oil in the lubricating oil viscosity range, diesters of various dicarboxylic acids, etc. may be inhibited to prevent rusting of lubricated surfaces by combining therewith relatively minute quantities of certain alkyl or alkylene derivatives of either succinic acid or succinic acid anhydride. Thus, derivatives of succinic acid or succinic acid anhydride containing a single aliphatic hydrocarbon chain containing from about to about 15 carbon atoms and preferably from about 8 to 12 carbon atoms in the aliphatic chain are employed in accordance herewith. Typical of such compounds are octenyl succinic anhydride, octenyl succinic acid, etc.

The term hydrophobic as employed herein to specificially describe certain silica thickeners is used in its customary sense. Thus, for example, the hydrophobic character of such a silica product can be shown in a particular instance by shaking a small quantity of it in a test tube with water to which there has been added an alcohol such as normal butanol. After agitating the mixture and settling, distinct layers of butanol and water are formed. If the silica is hydrophobic, it will rise above the water and either pass into suspension in the normal butanol layer or remain at the interface. For the most part, hydrophobic silicas and particularly those preferred for use herein are preferentially organophilic and will pass into the alcohol in such an experiment.

Various methods for improving the water resistance of greases prepared by thickening an oil with silica are known to the prior art and no invention is claimed herein for any method of preparing such thickeners or for such greases themselves. A particularly suitable silica product which is both hydrophobic and organophilic and which has been found to be of exceptional value as a grease thickener is a supercolloidal powder composed of an inorganic siliceous substrate having reacted on the surface thereof, a primary or secondary alcohol. Alcohols of about 18 carbon atoms or less are ordinarily employed for the purpose and preferably those containing from 2 to about 12 carbon atoms. Specifically, butoxy groups derived from butanol have been found very suitable. The alcohols are chemically bound to the substrate by esterification to give a plurality of OR groups thereupon. Hydrophobic-organophilic finely divided siliceous solids of this type are described in U. S. 2,676,148 issued to R. K. ller, April 20, 1954. Such silica products are referred to as estersils. Both the characteristics and preparation of this particular silica product will be hereinafter described in greater detail.

Greases comprising organic oleaginous vehicles and silica thickeners, in general, exhibit very poor rust preventive properties and it is to the improvement of these properties by addition of the herein described derivatives of succinic acid or its anhydride that this invention is particularly directed.

Particularly suitable organic vehicles for use in accordance herewith are mineral oils in the lubricating oil viscosity range, i. e. from about 50 S. S. U. at F. to about 300 S. S. U. at 210 F. These are preferably solvent extracted oils, from which substantially all the low V. I. constituents are removed with a solvent such as phenol, furfural, B,B-dichlorodiethyl ether (Chlorex), liquid S02, nitrobenzene, etc. Synthetic lubricating oils resulting from polymerization of unsaturated hydrocarbons or other oleaginous materials within the lubricating oil viscosity range such as high molecular weight polyoxyalkylene compounds, e. g. polyalkylene glycols and esters thereof, alipltatic diesters of dicarboxylic acids such as the butyl, hexyl, Z-ethyl-hexyl, decyl, lauryl, etc. esters of sebacic acid, adipic acid, azelaic acid, etc. may be thickened by the hydrophobic silica and employed in accordance herewith. Mixtures or blends of these vehicles may be employed in accordance herewith.

An organophilic silica of the type described in detail in U. S. 2,676,148, supra, is marketed by E. I. du Pont & Company under the trade name Estersil GT. These organophilic hydrophobic powders are composed of particles having at least one dimension of at least 150 millimicrons and thus are referred to as being supercolloidal. Often the amorphous silica substrate, as prepared, is com posed of particles considerably larger but being pulverulent it may be milled and broken down into smaller particle sizes. This supercolloidal organophilic silica, which may some times be referred to herein as hydrophobic silica," should have a specific surface area of from at least 25 to 900 mP/g. and preferably from about 200 to 400 m. g.

Briefly, the estersils which are employed as thickening agents in the present invention are powders or pulverulent materials having an internal structure, or substrate, of inorganic siliceous material having an average specific surface area of at least 25 square meters per gram (25 mF/g.) to whichOR groups are chemically bound, R being the hydrocarbon radical of a primary or secondary alcohol containing 2 to 18 carbon atoms-that is, a radical in which the carbon attached to the oxygen is also attached to hydrogen.

The substrates of the estersils are solid, inorganic, siliceous materials, containing substantially no chemically bound organic groups prior to esterification, and having silanol groups (-SiOH) on their surfaces. They can be mineral or synthetic in origin and thus can be amorphous silica. insoluble metal silicates, or such silicates coated with amorphous silica. The substrate is in particulate form. the particles being of supercolloidal-that is, larger than colloidal-size, and hence generally larger than 150 rnillimicrons in at least one dimension. Such particles may be aggregates of much smaller particles, i. e., ultimate units, which are so firmly attached to each other that they are not readily separated by simple stirring in a fluid medium.

In estersils to be used in the present invention substrate particles are preferred in which the ultimate units have an average diameter greater than rnillimicrons or in which the ultimate units are below 10 rnillimicrons and are joined in very open networks (large pore size). Preferably, the inorganic siliceous substrates used are porousthat is, they have exposed surfaces, in the interior of the particles, which are connected to the exterior so that liquid and gases can penetrate the pores and reach the exposed surfaces of the pore walls. Solids having average pore diameters of at least 4 rnillimicrons are specially preferred.

Suitable substrates have a specific surface area of at least m. /g and preferably of at least 200 m. /g., as determined by the nitrogen adsorption method described by P. H. Emmett in Symposium on New Methods for Particle Size Determination in Sub-Sieve Range, published by A. S. T. M., March 1941, p. 95, using a value of 0.162 square millimicron for the area covered by one surface-adsorbed nitrogen molecule in the calculations. For precipitated amorphous silica, a preferred substrate, there is an optimum range of about 200 to 400 m. g. Very voluminous siliceous aerogels having surface areas as great as 900 mfi/g, and preferably from 200 to 900 m. /g., are very suitable substrates because of the great thickening etficiency of estersils made from them.

The pore volumes of substrates are determined from nitrogen adsorption isotherms as described by Holmes and Emmett in Journal of Physical and Colloid Chemistry, 51, 1962 (1947), and from the volumes, pore diameters are calculated, assuming cylindrical pore structure.

Determinations of particle size and shape of substrate material may be made using various microscopic techniques including the light microscope and the electron microscope, the latter being described in detail by J. H. L. Watson in Analytical Chemistry 20, 576, 1948.

While various inorganic, siliceous solids having properties as aforementioned can be used as substrates for making estersils for use in the oil-grease compositions of this invention, precipitated amorphous silica is preferred. This silica consists of coherent aggregates of nonporous ultimate units in which the ultimate units are quite uniform in size and have an average diameter greater than about 10 rnillimicrons or ultimate units below 10 millimicrons diameter joined in very open networks.

Instead of silica, insoluble metal silicates can be used a the substrate. These may be prepared by treating soluble silicates with salts or hydrous oxides of metals other than alkali metals, and the insoluble silicates so obtained may be activated for surface esterification by washing with acids to remove a portion of the metal ions and leave surface silanol groups. Similarly, naturally occurring crystalline metal silicates may be acid-treated to provide esterifiable substrates. Alternatively or additional- 1y, silanol groups can be provided on the surfaces of metal silicates by coating them with a layer of amorphous silica, as by treating sodium silicate with an acid under such conditions that the silica so formed will deposit as a coating on the mineral particles. Mineral crystalline silicates which may be treated to provide suitable substrates include asbestos, such as chrysotile; clays, such as kaolins and bentonite; and micaceous minerals, such as vermiculite.

To make an estersil for use in the present invention a suitable substrate as above described is reacted with a primary or secondary monohydric alcohol. Alcohols of this class include: Normal straight chain alcohols such ethyl, n-propyl, n-b'utyl, n-amyl, n-hexyl, n-he-ptyl, noctyl, n-nonyl, n-decyl, n-undecyl, lauryl, myristyl, cetyl, and stearyl; branched chain primary alcohols such as isobutyl, isoamyl, 2,2,4-trimethyl-1 hexanol and 5,7,7-trimethy1-2-(l,3,3-trimethylbutyl)-1-octanol; secondary alcohols such as isoproyl, sec-butyl, Z-pentanol, 2-octanol, 4-methyl-2-pentanol, and 2,4-trimethyl-3-pentanol; alicyclic alcohols such as cyclopentanol, cyclohexanol, cycloheptanol, and menthol; alcohols having ethylenic unsaturation such as allyl, crotyl, oleyl, citronellol, and geraniol; alcohols having acetylenic unsaturation such as propargyl; and araliphatic alcohols such as benzyl, 2- phenylethanol, hydrocinnamyl, alphamethylbenzyl, and cinnamyl. Estersils made with the saturated primary and secondary alcohols are preferred, the preferred ester group thus being alkoxy. Technically, there is no upper limit on the number of carbon atoms in the ester group, but as a practical matter those having up to 1.8 carbons include the majority of groups derived from commercially available monohydric alcohols and offer a selection generally adequate. Mixtures of alcohols can be used for the esterifying agent. Alcohols containing from 3 to 6 carbons are especially preferred, since the estersils made therefrom are more stable against hydrolysis than those made from alcohols of fewer carbons and more economi- 1rial to use than those made from alcohols of more carons.

To esterify the substrate with the alcohol these two reactants are mixed under suitable anhydrous conditions. The substrate is preferably freed of extraneous material and the pH is adjusted to the range of 5 to 8 before the esterification reaction is started. During the reaction the water content of the liquid phase of the system is maintained at 5% by weight or less to give organophilic prodnets, 3% or less for hydrophobic products, and 1.5% or less for estersils of maximum esterification. Water may be removed to below these maxima by methods known to the art, azeotropic distillation being preferred. An especially preferred practice is to use as the azeotropic dehydrating agent the alcohol, such as n butanol, which is also being used as the esterifying agent.

The esterification reaction is carried out at an elevated temperature, the temperature having a direct bearing on the reaction time. The type of alcohol and water content are also related factors. Temperatures substantially bewherein R and R are acyclic hydrocarbon radicals containing from about to about carbon atoms and preferably from about 8 to 12 carbon atoms. Examples of compounds suitable for such use are either succinic acid or succinic anhydride containing alkyl or alkenyl groups such as amyl, pentenyl, octyl, octenyl, decyl, decenyl, dodecyl (lauryl), dodecenyl, pentadecyl, pentadecenyl, etc. Specifically, octenyl succinic anhydride and dodecenyl succinic anhydride, have been found to have particularly outstanding properties in this regard. These succinic anhydrides and acids effectively inhibit the formation of rust on lubricated surfaces when employed in lubricating greases of the above type in amounts ranging from about .05% to about 5.0% by weight and preferably from about 0.2% to about 1.5% by weight. Greater amounts can, of course, be employed; but, economically, it is disadvantageous to do so since no substantial advantage is gained thereby. These rust preventive additives are preferably introduced to the grease during the initial slow mixing operation to assure complete distribution in the grease.

Aliphatic derivatives of succinic acid and succinic acid anhydride are preferably prepared by condensing maleic acid anhydride and an individual olefin or a mixture of olefins at an elevated temperature and if desired in the presence of a mild condensing agent. The resulting alkenyl succinic acid anhydride may then be hydrolyzed to liberate the free alkenyl succinic acid or it may be hydrogenated to produce an alkyl succinic acid anhydride or it may be both hydrolyzed and hydrogenated to give alkyl succinic acids. In accordance with the present invention, olefins containing from about 5 to about 15 carbon atoms, c. g. pentene, hexene, nonene, dodecene, tridecene, tetradecene, pentadecene, etc. and mixtures of such olefins may be reacted with maleic acid anhydride to produce compounds suitable for addition to organophilic silica thickened greases. Mixtures of olefins in the above defined range obtained from the hydrocarbon synthesis process wherein carbon monoxide and hydrogen are converted to hydrocarbons and oxygenated compounds in the presence of an iron catalyst or the like; from cracking of petroleum hydrocarbons, etc. are suitable for such reaction.

in Table l are set forth data on a plurality of greases wherein the amount of silica thickener and lubricating vehicle are held constant and succinic anhydride and various derivatives thereof are tested as rust preventive additives in a humidity cabinet test. In the humidity cabinet test, polished or sand blasted cold-rolled S. A. E. I020 steel panels, 2" x 3" x Ms were coated with 0.5 g. of test grease and suspended in an atmosphere of 100% humidity at 100 F. The humidity cabinet is provided with heating units and thermo regulators for automatic temperature control. A water level of about 6 inches is maintained at the bottom of the cabinet to give approximately l00% humidity at all times. The steel panels are coated with the grease and suspended by glass hooks from a revolving stage in the humidity cabinet. From 1 to 1.5 complete changes of saturated air per hour are provided in the cabinet. The test panels were examined daily and at the end of the test run, the panels were viewed by several observers and were judged on the basis of a rating from 1 to 10 (i. e. from no rust to badly rusted). Two panels were coated with each grease and the data given are based upon the average rating of the two. in no instance was there any substantial diiference between panels coated with a given grease. The greases employed in the tests comprised a solvent extracted S. A. oil thickened with an orgauophilichydrophobic silica (iistersil GT"-product of E. I. du Pont 81 Co.) which corresponds to the supercolloidal organophilic silica prepared as described above. With the exception of Example l wherein no anti-rust additive was employed and the relative percentages of silica and oil were 13% and 37% by weight respectively, the other compositions solvent extracted 8. A. E. 40 oil.

Additive Rust Rating Grease Sample polymeri- The use of an oil soluble emulsifier and an oiliness agent in combination with the succinic acid or anhydride derivatives has indicated considerable improvement in rust prevention even though the use of these same additives without a suitable derivative of succinic acid or anhydride results in no substantial protection from rust. in particular, dialkyl phosphates wherein the alkyl radicals contain from about 6 to about l8 carbon atoms and preferably from about 8 to about 12 are the preferred oiliness agents and pentaerythritol mono-oleate is the preferred emulsifier. Thus, set forth in Table 2 are data demonstrating the synergistic effect of combining a suitable succinic anhydride derivative with certain commercial petroleum additives in a silica thickened grease. The grease samples listed in Table 2, unless otherwise indicated, consisted of 13% hydrophobic silica (Du Ponts Estersil GT"), 0.2% Du Pont metal deactivator (an solution of N:N'-disalicylidcne-l :2 diaminopropane in xylene), 1.0% tricresyl phosphate, 0.5% of a mixture of aromatic amines (Ortholeum 300), 0.2% of a derivative of succinic anhydride and the balance consisted of These various compounds are added for their usual purpose to the commercial samples on which the following data were obtained and although it would be preferred to show the elfect of the emulsifier and oiliness agent in the absence of these materials, the fact that they are constant in amount throughout the tests serves to eliminate them as an anti-rust factor.

Table 2 Grease Sample Succlnic Anhydridc Deriva- Other Ad- Rust.

tivc ditlvc Rating 1.. Dodccyl 5 succinic auhydridc. 2. Octcnyl succinic unhydridc. t). .....do. .75

4 Octcnyl succinic anhydride 'SJgQ/E 1 i a 5 Nonc 1.00;,A.... 10 6... .(lo... t.l.5,,. ll... 10 1.09. A 7 [{05372 8 A=Pcntamul 126-tcchnleal grade of pcntacrythritol nionoolcutv in the form of a clear, amber colored oil with Acid No. of about An all purpose oil soluble emulsifier. Product of Hcydcn Chemical Corp.

B=Ortholeurn 162-A phosphate of long chain alcohols (predominately C1 Light brown viscous liquid with a freezing: point. of about. 15 0.. hip. (lr. 0.99. An oiliucss agent and film strength initirover. Product of E. I. du Pout & C0.

3 A branched chain C1 hydrocarbon radical.

0.5% of octcnyl succinic nnhydrtdc employed rather than 0.17;, as in other samples.

Because of the excellent high temperature stability of hydrophobic silica thickened greases. applications in steel mills on plain, anti-friction, and roller bearings as well as on roller chains are just a few of the typical promising uses of these materials. in addition, these materials have been employed on wheel bearings of transport fleets, in gear cases of mechanical ironers, oven conveyor bearings, kiln car bearings, and in motor bearings operated under low about 100 C. are unsuitable. Obviously, the temperature should not exceed the thermal decomposition point of the alcohol in the presence of the substrate nor the point of thermal stability of the estersil. Preferably the heating is not prolonged any more than required to achieve esterification equilibrium.

After the esterification reaction, any excess alcohol present may be removed by conventional methods, such as distilling it off or filtering off the estersil.

The esterified inorganic siliceous solids, the estersils, are in the form of powders, or sometimes lumps or cakes pulverable under the pressure of the finger or by a light rubbing action. They are generally exceedingly fine, light, flufly, voluminous powders, as indicated by the fact that they have low bulk densities. Especially easy to disperse in lubricating oils according to this invention are estersils having a bulk density not greater than 0.20 gram per cubic centimeter under a compressive load of 3 lbs./ sq. inch, and not greater than 0.30 g./cc. at 78 lbs/sq. inch. However, in certain cases, it may be desirable to use higher bulk density material to facilitate handling.

The esterification reaction does not substantially change the structure of the inorganic siliceous solid or substrate which was esterified. In other words, the internal structure of the estersil, the structure to which the -OR groups are chemically bound, has substantially the same particle size, surface area, pore diameter, and other characteristics described previously in the discussion of the substrate material. The estersil particles are in a supercolloidal state of subdivision.

In order to make an inorganic siliceous solid organophilic, it is necessary to react a certain minimum proportion of the surface silanol groups with an alcohol containing at least 2 carbon atoms. With most alcohols, the esterified material becomes organophilic when it contains more than about 80 ester groups per 100 square millimicrons of surface of the internal structure or substrate. The products are markedly organophilic when there are chemically attached more than about 100 ester groups per 100 square millimicrons of substrate surface.

Estersils, the organophilic, are also hydrophilic unless more highly esterified. Thus while they prefer normal butanol to water in a butanolwater system, they will in the absence of an organic phase wet into water also. The preferred estersils, however, are those which are more highly csterified so that they are not only organophilic but are also hydrophobic, that is, they will not wet into water even in the absence of an organic phase. Such organophilic and hydrophobic products are obtained by esterifying the inorganic siliceous material to give an estersil containing at least 200 ester groups per 100 square millimicrons of substrate surface.

Hydrophobic estersils can be made without esterifying all the surface silanol groups. However, in order to obtain cstersils having maximum stability toward hydrolysis, it is necessary that the ester groups be crowded together so closely on the surface that the surface is completely protected. For most ester groups, especially for those containing 3 to 6 carbon atoms, this requires at least about 270 and as many as 300-400 ester groups per 100 square millimicrons.

Set forth below is a description of a method for preparing a supercolloidal organophilic silica product of the type described:

One volume of a solution of 0.48 N sulfuric acid is added at a uniform rate, over a period of 30 minutes, at a temperature of about 30 C., to three volumes of a solution of sodium silicate, containing 2% SiOz and having a molar SiOzzNazO ratio of 3.36. The amount of sulfuric acid solution is adjusted so that it is equivalent to 80% of the NazO in the original sodium silicate. The pH during this process drops from 11.3 to about 9. The clear sol contains tiny discrete particles of silica having an average diameter of less than millimicrons. Violent agitation is provided to insure complete and instantaneous mixing.

The temperature during the entire reaction is maintained below 40 C. The clear sol resulting from this process step and containing 1.5% SiOz, is called the heel. The heel is heated to C. Solutions of sodium silicate and sulfuric acid are added simultaneously at a uniform rate over a period of two hours. The sodium silicate solution contains 10% SiOz and has a molar SiOzzNazO ratio of 3.36. Enough 4% sulfuric acid solution (approximately equal in volume to the sodium silicate solution) is added so that 80% of the NazO in the silicate solution is neutralized during the additional step. The addition of silicate and acid is continued until one part of SiOz has been added for each part of SiO2 present in the heel. During the additions the pH of the heel slowly rises from 9 to 10 and is then maintained at about 10. The sodium ion concentration remained below 0.3 N throughout the process. Vigorous agitation is employed so that the mixing is essentially instantaneous. A silica precipitate is thus obtained.

A 2% solution of a mixture of cetyl and lauryl tri methylammonium bromide, 0.16% of the mixed compounds is added, based on the weight of the silica. The slurry is filtered and the wet filter cake reslurried in water. The reslurry is adjusted to about pH 7 with dilute sulfuric acid, and then filtered and the filter cake washed with Water.

This filter cake as obtained on a vacuum filter contains about 12.5% by weight of SiOz. The specific surface area of the siliceous substrate of a number of batches thus prepared and reduced to powdered form by drying in air at 120 C. ranges from about 250 to 365 mF/g. and averages about 300 m. /g.

The substrate, prepared as above, is esterified by mixing the wet filter cake with about an equal weight of n-butanol, and the pH of the mixture adjusted to 5.5 with HCl. The mixture is then heated to remove water by azeotropic distillation at a reflux ratio of 2:1 while adding butanol to maintain the original volume of the slurry in the still. The distillation is continued until the distillate no longer separates into two layers and the still temperature rises to C., indicating that most of the water has been removed. The reflux ratio is then increased to 10:1 or greater and the distillation continued for about eight hours at a temperature of about 118 C. After the refluxing is complete, the slurry is cooled and filtered, and the cake dried on a steam bath until there is substantially no butanol odor. The cake is then oven-dried at 120 C. for 24 hours, and the dry product ground by suitable means to a fluffy white powder.

Greases of the present invention are preferably prepared by mixing a uniform slurry of the silica and lubricant vehicle in a conventional grease kettle or similar slow speed mixer and then milling said mixture in a colloid mill, 3-roll mill, extrusion mill, etc. The method of preparing these greases in general is quite different from that ordinarily employed in preparing soap thickened greases in that no heating of constituents is required although it is permissible. Amounts of from about 5 to about 20% by weight or more of the herein described thickener may be employed in grease preparation and preferably from about 8 to about 15%. An amount of about 12% of the above specifically described thickener results in an N. L. G. I. No. 2 grade grease.

For the purpose of preventing corrosion of surfaces lubricated by greases embodying the above components, there is added in accordance herewith, a succinic acid or succinic acid anhydride derivative having the following empirical formulae:

various conditions of moisture and heat. Freedom from rust of surfaces lubricated by these materials is apparent in each instance.

In addition to the rust preventive material employed as an additive and the other additives referred to in addition to Table 2 above, various other commonly employed additives for lubricant greases may be used without in any Way departing from the present invention. Thus, additional fillers, dies, odorant materials, extreme pressure additives, etc., may be employed.

This application is a continuation-in-part of our copending application Serial No. 345,702, filed March 30, 1953, now abandoned.

While we have described our invention with particular reference to certain preferred embodiments thereof, it is to be understood that these are by way of illustration and not of limitation. What we claim as novel and desire to protect by Letters Patent is as follows:

1. A lubricant grease comprising a major proportion of a mineral lubricating oil, from about 5% to about 20%, by weight, of an organophilic solid thickener consisting essentially of substrate particles of inorganic siliceous materials in a supercolloidal state of subdivision having chemically bound thereto -OR groups, wherein R is a hydrocarbon radical having 2 to 18 carbon atoms in which the carbon atom attached to the oxygen is also attached to at least one hydrogen atom, the substrate particles having a specific surface area of from about 25 to 900 mfi/ g. and having a sufiicient number of chemically bound OR groups per unit of substrate surface area to cause them to be preferentially wetted by butanol in a butanol-water mixture, from about 0.2% to about 5% by weight, of a rust preventive compound selected from the group consisting of an alkenyl succinic anhydride, an alkenyl succinic acid, an alkyl succinic anhydride and an alkyl succinic acid wherein the alkenyl and alkyl radicals contain from about 8 to about 12 carbon atoms, from about 0.05% to about 1% by weight of pentaerythritol mono-oleate and from 0.5% to 1% by weight of a dialkyl phosphate in which the alkyl group contains from about 6 to about 18 carbon atoms.

2. The lubricant grease of claim 1 wherein the rust preventive compound comprises octenyl succinic anhydride.

3. The lubricant grease of claim 1 wherein the rust preventive compound comprises dodecyl succinic anhydride.

4. The lubricant grease of claim 1 wherein the rust preventive compound comprises octenyl succinic acid.

5. The lubricant grease of claim 1 wherein the rust preventive compound comprises octyl succinic acid.

6. The lubricant grease of claim 1 wherein the rust preventive compound comprises octyl succinic anhydride.

References Cited in the file of this patent UNITED STATES PATENTS 2,133,734 Moser Oct. 18, 1938 2,647,872 Peterson Aug. 4, 1953 2,658,869 Stross et al Nov. 10, 1953 2,676,148 Iler Apr. 20, 1954 

1. A LUBRICANT GREASE COMPRISING A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL, FROM ABOUT 5% TO ABOUT 20%, BY WEIGHT, OF AN ORGANOPHILIC SOLID THICKENER CONSISTING ESSENTIALLY OF SUBSTRATE PARTICLES OF INORGANIC SILICEOUS MATERIALS INA SUPERCOLLOIDAL STATE OF SUBDIVISION HAVING CHEMICALLY BOUND THERETO -OR GROUPS, WHEREIN R IS A HYDROCARBON RADICAL HAVING 2 TO 18 CARBON ATOMS IN WHICH THE CARBON ATOM ATTACHED TO THE OXYGEN IS ALSO ATTACHED TO AT LEAST ONE HYDROGEN ATOM, THE SUBSTRATE PARTICLES HAVING A SPECIFIC SURFACE AREA OF FROM ABOUT 25 TO 900M.2/G. AND HAVING A SUFFICIENT NUMBER OF CHEMICALLY BOUND -OR GROUPS PER UNIT OF SUBSTRATE SURFACE AREA TO CAUSE THEM TO BE PREFERENTIALLY WETTED BY BUTANOL IN A BUTANOI-WATER MIXTURE, FROM ABOUT 0.2% TO ABOUT 5% BY WEIGHT, OF A RUST PREVENTIVE COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN ALKENYL SUCCINIC ANHYDRIDE, AND ALKENYL SUCCINIC ACID, AN ALKYL SUCCINIC ANHYDRIDE AND AN ALKYL SUCCINIC ACID WHEREIN THE ALKENYL AND ALKYL RADICALS CONTAIN FROM ABOUT 8 TO ABOUT 12 CARBON ATOMS, FROM ABOUT 0.05% TO ABOUT 1% BY WEIGHT OF PENTAERYTHRITOL MONO-OLEATE AND FROM 0.5% TO 1% BY WEIGHT OF A DIALKYL PHOSPHATE IN WHICH THE ALKYL GROUP CONTAINS FROM ABOUT 6 TO 18 CARBON ATOMS. 